Darwin was a good scientist, and was conducting science based on what was known or believe in his time. A lot of scientific progress has been made in the last century and a half after
Descent of Man was published. For one thing, there is much more genetic variation
within each "race" than there are between "races". Racial characteristics are now accepted to be very superficial characteristics in what is a population of very closely related individuals.
What Darwin thought 150 years ago has very little interest in the current state of science. Perhaps, though, your interest is history?
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